Wellbore distributed sensing using fiber optic rotary joint

Abstract

A system includes an optical fiber integrated into a conveyance subsystem that is positionable downhole in a wellbore. The system also includes a backscattering sensor system positionable to monitor temperature and optical fiber strain along the optical fiber using backscattered light signals received from the optical fiber. Further, the system includes a fiber optic rotary joint positionable to optically couple the optical fiber with the backscattering sensor system to provide an optical path for the backscattered light signals to reach the backscattering sensor system.

What is claimed is: 
     
       1. A system, comprising:
 an optical fiber integrated into a conveyance subsystem that is positionable downhole in a wellbore; 
 a backscattering sensor system positionable to monitor temperature and optical fiber strain along the optical fiber using backscattered light signals received from the optical fiber; 
 a fiber optic rotary joint positionable to optically couple the optical fiber with the backscattering sensor system to provide an optical path for the backscattered light signals to reach the backscattering sensor system; and 
 a temporal filtering system positionable to separate temperature components and optical fiber strain components from a temperature and optical fiber strain profile using a rate of change of the temperature components and the optical fiber strain components of the temperature and optical fiber strain profile generated by the backscattering sensor system. 
 
     
     
       2. The system of  claim 1 , further comprising a reel positionable to store at least a portion of the conveyance subsystem during deployment of the conveyance subsystem downhole within the wellbore. 
     
     
       3. The system of  claim 1 , wherein the backscattering sensor system is positionable to monitor the temperature and the optical fiber strain along the optical fiber while the conveyance subsystem is deployed into or removed from the wellbore. 
     
     
       4. The system of  claim 1 , wherein the optical fiber is positionable to receive wavelength division multiplexed light signals from additional laser interrogation instruments while the backscattering sensor system monitors temperature and optical fiber strain along the optical fiber. 
     
     
       5. The system of  claim 1 , wherein the backscattering sensor system comprises a Brillouin optical time domain sensor system, a coherent Rayleigh instrument, or a Raman instrument, and wherein the backscattering sensor system is positionable to monitor the temperature and the optical fiber strain along an entire length of the optical fiber. 
     
     
       6. The system of  claim 1 , further comprising:
 a downhole tool attached to a downhole end of the conveyance subsystem, wherein the backscattering sensor system is positionable to monitor the temperature and the optical fiber strain along the optical fiber during operation of the downhole tool. 
 
     
     
       7. The system of  claim 6 , wherein the downhole tool comprises a wireline logging tool, a perforating tool, a wellbore completion tool, a telemetry tool, or a combination thereof. 
     
     
       8. A method, comprising:
 deploying an optical fiber downhole within a wellbore; 
 transmitting, by a Brillouin optical time domain sensor system, a light signal through a fiber optic rotary joint into the optical fiber; 
 receiving, by the Brillouin optical time domain sensor system, a backscattered light signal from the optical fiber through the fiber optic rotary joint; 
 analyzing, by the Brillouin optical time domain sensor system, the backscattered light signal to monitor temperature and optical fiber strain along the optical fiber; and 
 separating, by a temporal filtering system, temperature components and optical fiber strain components from a temperature and optical fiber strain profile using a rate of change of the temperature components and the optical fiber strain components of the temperature and optical fiber strain profile generated by the Brillouin optical time domain sensor system. 
 
     
     
       9. The method of  claim 8 , wherein transmitting the light signal through the fiber optic rotary joint into the optical fiber is performed while the optical fiber is run into or out of the wellbore. 
     
     
       10. The method of  claim 8 , wherein analyzing the backscattered light signal to monitor the temperature comprises filtering out a strain component from the backscattered light signal, and analyzing the backscattered light signal to monitor the optical fiber strain comprises filtering out a temperature component from the backscattered light signal. 
     
     
       11. The method of  claim 8 , wherein analyzing the backscattered light signal to monitor the temperature comprises removing an optical fiber strain component of the backscattered light signal by comparing a temperature and optical fiber strain profile generated using the backscattered light signal to a baseline temperature profile and correcting portions of the temperature and optical fiber strain profile that depart from the baseline temperature profile. 
     
     
       12. The method of  claim 8 , wherein receiving the backscattered light signal is performed while a downhole tool performs a downhole operation within the wellbore. 
     
     
       13. The method of  claim 8 , wherein receiving the backscattered light signal is performed during a wellbore stimulation operation. 
     
     
       14. The method of  claim 8 , wherein deploying the optical fiber within the wellbore is performed by rotating a reel coupled to the fiber optic rotary joint and storing undeployed portions of the optical fiber. 
     
     
       15. A downhole optical fiber sensing system, comprising:
 an optical fiber positionable downhole within a wellbore; 
 a Brillouin optical time domain sensor system positionable to monitor temperature and optical fiber strain along the optical fiber using backscattered light signals received from the optical fiber while running the optical fiber into or out of the wellbore; 
 a fiber optic rotary joint positionable to optically couple the optical fiber with the Brillouin optical time domain sensor system to provide an optical path for the backscattered light signals to reach the Brillouin optical time domain sensor system; and 
 a temporal filtering system positionable to separate temperature components and optical fiber strain components from a temperature and optical fiber strain profile using a rate of change of the temperature components and the optical fiber strain components of the temperature and optical fiber strain profile generated by the Brillouin optical time domain sensor system. 
 
     
     
       16. The system of  claim 15 , wherein the optical fiber is integrated into a coiled tubing, a wireline, or a slickline. 
     
     
       17. The system of  claim 15 , further comprising a reel positionable to store at least a portion of the optical fiber during deployment of the optical fiber downhole within the wellbore. 
     
     
       18. The system of  claim 15 , wherein the Brillouin optical time domain sensor system is positionable to monitor the temperature and the optical fiber strain along the optical fiber simultaneously. 
     
     
       19. The system of  claim 15 , wherein the optical fiber comprises a length of between 10 km and 40 km, and wherein the Brillouin optical time domain sensor system is positionable to monitor the temperature and strain along the length of the optical fiber.